Farther south on the shore of California the Indians used the marine bivalve Saxidomus gracilis, while in the islands close to the shore another bivalve was in common use.
The Algonquin tribes of the east coast of North America used elaborate belts of beads called wampum which was cut from the purple part of the shell of the marine bivalve Mercenaria mercenaria, more commonly known as the hard clam, quahog, or when young, the littleneck clam.
As the value of the cowry was much greater in West Africa than in the regions from which the supply was obtained, the trade was extremely lucrative. In some cases the gains are said to have been 500%. The use of the cowry currency gradually spread inland in Africa. By about 1850 Heinrich Barth found it fairly widespread in Kano, Kuka, Gando, and even Timbuktu. Barth relates that in Muniyoma, one of the ancient divisions of Bornu, the king's revenue was estimated at 30,000,000 shells, with every adult male being required to pay annually 1000 shells for himself, 1000 for every pack-ox, and 2000 for every slave in his possession.
In the countries on the coast, the shells were fastened together in strings of 40 or 100 each, so that fifty or twenty strings represented a dollar; but in the interior they were laboriously counted one by one, or, if the trader were expert, five by five. The districts mentioned above received their supply of kurdi, as they were called, from the west coast; but the regions to the north of Unyamwezi, where they were in use under the name of simbi, were dependent on Muslem traders from Zanzibar. The shells were used in the remoter parts of Africa until the early 20th century, but gave way to ordinary currency. The shell of the land snail, Achatina monetaria, cut into circles with an open center was also used as coin in Benguella, Portuguese West Africa. In parts of Asia Cyproeci annulus, the ring cowry, so-called from the bright orange-colored ring on the back or upper side of the shell, was commonly used. Many specimens were found by Sir Henry Layard in his excavations at Nimrud in 1845-1851.
In the islands north of New Guinea the shells were broken into flakes. Holes are bored through these flakes, which are then valued by length, as in the case of the American tuskshell, the measuring, however, being done between the nipples of the breasts instead of by the finger joints. Two shells are used by these Pacific islanders, one a cowry found on the New Guinea coast, and the other the common pearl shell, broken into flakes.
As late as 1882 local trade in the Solomon Islands was carried on by means of a coinage of shell beads, small shells laboriously ground down to the required size by the women. No more than were actually needed were made, and as the process was difficult, the value of the coinage was satisfactorily maintained.
The custom of breaking or flaking shells was common among some of the American Indian tribes, while in the South Pacific Islands the Oliva carneola was used.